CS&B - Histology - Epithelia; Connective Tissue Flashcards by Jason Worley

What two types of structure are present in all types of tissue?

Cells and ECM

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What are the four principal tissue types?

Muscle;

Epithelium;

Nervous;

Connective

(MENC)

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The four principal tissue types are very different from one another in regards to their ratio of cells to ____.

ECM

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What are some general functions of epithelial tissue?

Protection, absorption, secretion, sensory reception

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An epithelial cell membrane (and to some degree, portions of the cell) can be divided into what two main domains?

Apical and basolateral

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The apical side of an epithelial cell typically contacts what?

The lateral sides of an epithelial cell typically contacts what?

The basal side of an epithelial cell typically contacts what?

The external environment or a bodily cavity / lumen;

other cells;

the basement membrane

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Are epithelial cells polar?

How do they interact with surrounding cells?

Are they tightly attached to a basement membrane?

Yes;

tight attachments;

yes

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What is the longer, branching type of microvillous cellular projection found in the vas deferens?

Stereocilia (stereovili)

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What is unique about the epithelium of the PCT of the kidney?

Microvili

(a brush border)

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What protein connects the microtubule pairs to one another in the axoneme?

Nexin

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From the apex towards the base, what junctions unite adjacent epithelial cells?

Zona occludens (tight junctions)

Zona adherens

Macula adherens (desmosome)

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What junction connects epithelial cells to the basement membrane?

Hemidesmosomes

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The zona occludens (tight junction) is anchored by what major transmembrane protein(s)?

The zona adherens is anchored by what major transmembrane protein(s)?

The macula adherens (desmosome) is anchored by what major transmembrane protein(s)?

Occludins, claudins;

E-cadherins;

cadherin family proteins (e.g. desmoglein, desmocollin)

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Hemidesmosomes are anchored by what major transmembrane protein(s)?

Gap junctions are anchored by what major transmembrane protein(s)?

Integrins;

connexins

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What cytoskeletal structures are associated with epithelial gap junctions?

None

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What stain can illustrate the basement membrane?

Periodic acid-Schiff stain

(the basement membrane is made of glycoproteins)

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What are the two layers of the basement membrane?

A basal lamina;

a reticular lamina

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What specialized apical structure can be found on the epithelium of the small intestine?

What specialized apical structure can be found on the epithelium of the respiratory tract?

What specialized apical structure can be found on the epithelium of the kidney PCTs?

What specialized apical structure can be found on the epithelium of the vas deferens?

What specialized apical structure can be found on the epithelium of the oviducts?

Microvili (small intestine)

Cilia (respiratory tract)

Microvili (kidney PCTs)

Stereocilia/stereovili (ductus deferens)

Cilia (oviducts)

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The zona occludens (tight junction) connects to what type of cytoskeletal component?

The zona adherens connects to what type of cytoskeletal component?

The macula adherens (desmosome) connects to what type of cytoskeletal component?

Actin

Intermediate filaments (e.g. keratin)

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Hemidesmosomes connect to what type of cytoskeletal component?

Gap junctions connect to what type of cytoskeletal component?

Intermediate filaments

None

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The zona occludens (tight junction) connects to what type of cytoskeletal component?

They are largely made up of what transmembrane protein(s)?

Actin;

occludins, claudins

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The zona adherens connects to what type of cytoskeletal component?

They are largely made up of what transmembrane protein(s)?

Actin

E-cadherins

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The macula adherens (desmosome) connects to what type of cytoskeletal component?

They are largely made up of what transmembrane protein(s)?

Intermediate filaments (e.g. keratin)

Cadherins family proteins (e.g. desmogleins, desmocollin)

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Hemidesmosomes connect to what type of cytoskeletal component?

They are largely made up of what transmembrane protein(s)?

Intermediate filaments

Integrins

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Gap junctions connect to what type of cytoskeletal component? They are largely made up of what transmembrane protein(s)?

None Connexins

What cell junction type creates a sealed barrier between epithelial cells?

Zona occludens (tight junction)

What cell junction type connects the microfilaments of adjacent epithelial cells? What cell junction type connects the intermediate filaments of adjacent epithelial cells?

Zona adherens Macula adherens (desmosome)

What cell junction type connects the cytoplasm of adjacent epithelial cells? What cell junction type anchors epithelial cells to the basement membrane?

Gap junctions Hemidesmosomes

By what three categories are epithelial cells classified?

**Layer(s)** (simple, stratified, pseudostratified, transitional) **Shape** (squamous, cuboidal, columnar) **Keratinization** (keratinized or non-keratinized)

What is the name of the epithelial lining of blood vessel lumens? What is the name of the epithelial lining of lymph vessel lumens? What is the name of the interior epithelial lining of body walls and cavities?

Endothelium Endothelium Mesothelium

What is the name of the epithelial lining of the respiratory tract? What is the name of the epithelial lining of nasal cavity odor receptors? What is the name of the transitional epithelial lining of the bladder?

Respiratory epithelium Olfactory epithelium Urothelium

What are the two main types of gland?

Exocrine (duct-ed) Endocrine (duct-less)

Describe basic gland development (exocrine and endocrine).

Exocrine glands typically secrete their products in what two fluid types?

Serous Mucous

How does an apocrine gland release products? How does a merocrine gland release products? How does a holocrine gland release products?

Apical portion of cell becomes the secretion; secretory exocytotic vesicles; the entire cell dies and becomes the secretion

What does it mean for an exocrine gland to be unicellular? What does it mean for an exocrine gland to be multicellular?

Only one cell **type** is involved (e.g. goblet cells); multiple cell **types** are involved (e.g. stomach mucosa)

What type of epithelial tissue lines the inside of the heart? What type of epithelial tissue lines the outside of the heart?

Endothelium; mesothelium (both simple squamous endothelium)

How do endothelial and mesothelial cells appear on microscopy? What type of epithelial cells are these (layers and shape)?

Thin, flat, single layer with prominent nuclei and little cytoplasm; both simple squamous epithelium

Cells of the kidney tubules are primarily what type of epithelium? (Layers and shape)

Simple cuboidal epithelium

Can microvili be seen on light microscopy?

What type of epithelium makes up the mucosal border of the jejunum? (Layers and shape)

Simple columnar epithelium

What type of epithelium lines the tracheal lumen? (Layers and shape) Do each of these cells originate on the basement membrane? Do all reach the lumen?

Pseudostratified columnar epithelium; yes, no

Are cilia visible on light microscopy?

Yes

What type of epithelium lines the epididymis? (Layers and shape)

Psuedostratified columnar epithelium

What feature is found on the surface of the pseudostratified columnar cells of the epididymis?

Stereovilli

What type of epithelium lines the bladder?

Transitional epithelium

What shape are the epithelial cells of the bladder when the bladder is contracted? What shape are the epithelial cells of the bladder when the bladder is distended?

Done-shaped; flat

What type of epithelium lines the esophageal lumen?

Stratified squamous epithelium (nonkeratinized)

What type of epithelium makes up the epidermis?

Stratified squamous epithelium (keratinized)

What type of epithelium lines the duct of a sweat gland?

Stratified cuboidal epithelium

What type of epithelium lines the duct of a submandibular gland?

Stratified columnar epithelium

Besides occludins and claudins, what other notable two proteins contribute to the zona occludins?

The ZO1 and ZO3 proteins

Connective tissue, like all other tissues, is made of what two substances in particular?

Cells and ECM

The ECM of connective tissue is made of what two components in particular?

Fibers and ground substance

Are the cells or general tissues of connective tissue polarized?

How does the intercellular connectivity of epithelial cells relate to the intercellular connectivity of connective tissue cells?

Epithelial cells are highly interconnected; connective tissue cells are typically independent of one another

The ratio of ECM to cells is very ____ in connective tissue. The ratio of ECM to cells is ____ in epithelial tissue.

High; low

The ECM of connective tissue is made of protein fibers and ground substance. What are three major types of protein fiber found here?

Reticular, elastic, collagen | (**REC**)

The ECM of connective tissue is made of protein fibers and ground substance. What are three major types of ground substance found here?

Proteoglycans, glycosaminoglycans, glycoproteins (**PG-GAG-GP**)

The ECM of connective tissue is made of protein fibers and ground substance. What are three major types of protein fibers found here? What are three major types of ground substance found here?

*Protein fibers (**REC**)* - Reticular, elastic, collagen *Ground substance (**PG, GAG, GP**)* - proteoglycans, glycosaminoglycans, glycoproteins

The cells of connective tissues can generally be placed into what three categories based on activity?

**Resident** (permanent), **immigrant**, and **wandering** (transitory) cells

What are the resident, non-migratory cells of connective tissue (2)? What are the immigrant phagocytes of connective tissue (3)? What are the wandering phagocytes of connective tissue (3)?

Fibroblasts, adipocytes; mast cells, macrophages, plasma cells; leukocytes

What is the broad category of 'wandering,' migratory connective tissue cell?

Leukocytes (e.g. plasma cells) ## Footnote *(note: but not macrophages or mast cells)*

What is the main connective tissue cell responsible for synthesizing collagen / elastic fibers and secreting ground substance?

Fibroblasts

What connective tissue cell is primarily involved in allergic and inflammatory reactions?

Mast cells | (differentitated basophils)

Macrophages in the skin are known as: Macrophages in the liver are known as: Macrophages in the CNS are known as: Macrophages in the bone are known as:

Histiocytes; Kupffer cells; microglia; osteoclasts

Mast cells are derived from:

Basophils

Basophils enter connective tissue and differentiate into:

Mast cells

Mast cell granules primarily contain what three substances?

Histamine, heparin, eosinophil chemotactic factors

What cell balances the effects of mast cells? How?

Eosinophils; arylsulfatases, histaminase, heparinase

What type of cell is shown in this electron micrograph?

Mast cell

What type of cell is apparent in this light micrograph?

Eosinophil ## Footnote *(characterized by many eosinophilic granules)*

What cell is degranulated by IgE cross-linking and is responsible for immediate allergic reactions? This cell is derived from what other cell? What cell is an 'anti-allergy' cell that cancels out the effects?

Mast cell; basophil; eosinophil

Describe the nucleus of an eosinophil. Describe the nucleus of a neutrophil. Describe the nucleus of a plasma cell.

Bilobed; segmented, PMN; clockface

What shape is a fibroblast?

Spindle-shaped

The nucleus of what cell could be described as an eccentric clock-face nucleus?

A plasma cell

What type of cell is apparent in this light micrograph?

A plasma cell

What type of cell is apparent in this light micrograph?

A lymphocyte

What is the most abundant protein type in the body?

Collagen

What is the largest diameter collagen fiber? What is the smallest diameter collagen fiber?

Type I; Type VII *(decrease in diameter as they increase in type number)*

What is the main type of collagen banded fiber found in bones, tendons, ligaments, dentin, and skin? What is its main property?

Type I; tensile strength

What is the main type of collagen fiber found in hyaline and elastic cartilage?

Type II

What is the first type of collagen synthesized in wound healing? It is synthesized as a portion of what type of fiber? What stain is used for its visualization?

Type III; reticular fibers; silver stain

What type of collagen fiber attaches as single molecules to help make up the basement membrane? To what basement membrane protein do they attach? In which layer of the basement membrane?

Type IV; laminin; basal lamina

What type of collagen is known as an 'anchoring' collagen? What does it anchor together?

Type VII; the basal lamina and reticular lamina

What type of collagen is most abundant? Where is it found? What types of cartilage contain large amounts of type II collagen? What is another name for type III collagen? Where is type IV collagen most abundant? What is type VII collagen's main role?

Type I, bone/scar tissue/tendons/dentin/dermis/organ capsules/ligaments/etc.; hyaline/elastic cartilages; reticular (net- or mesh-like) collagen; the basal lamina (in the basement membrane); as an anchoring structure

In wound healing, type ___ collagen is initially laid down and later replaced by type ___ collagen.

III; I

What type of collagen is most abundant? Where is it found?

Type I; bone/tendons/scar tissue/dentin/dermis/organ capsules/ligaments/etc.

What two types of cartilage contain large amounts of type II collagen?

Hyaline and elastic cartilages

What is another name for type III collagen?

Reticular (net- or mesh-like) collagen

Where is type IV collagen most abundant? In what form? Bound to what?

The basal lamina (of the basement membrane); individual molecules; laminin

What is type VII collagen's main role?

As an anchoring structure (between the basal lamina and reticular lamina)

Silver stain is useful in visualing what type of collagen?

Type III

Most connective tissue cells come from what two origin sources?

Mesenchymal cells; hematopoeitic stem cells

Type IV collagen is found in which layer of the basement membrane?

The basal lamina | (as opposed to the reticular lamina)

What two types of collagen are found in the basement membrane? Which one is in the basal lamina attached to laminin? Which one anchors the basal lamina to the reticular lamina?

IV, VII; IV; VII

What type of fibroblast specifically makes large amounts of reticular fibers? What type of fibroblast specifically makes bone stroma? What type of fibroblast specifically makes dentin? What type of fibroblast specifically makes cartilage?

A reticular cell; an osteoblast; an odontoblast; a chondroblast

Smooth muscle cells can synthesize what types of fibers?

Collagen I and III; elastin

Kupffer cells, histiocytes, microglia, and osteoclasts all derive from what common cell? Reticular cells, osteoblasts, chondroblasts, and odontoblasts all derive from what common cell?

Macrophage; fibroblast

What type of immature collagen do fibroblasts secrete out of the cell?

Procollagen

Procollagen is synthesized where? What else happens to this strand of procollagen in this location?

The RER; **hydroxylation** of proline and lysine, **glycosylation**, **disulfide** **bond** formation

Procollagen is hydroxylated and glycosylated and then sent where?

The Golgi apparatus for packaging and exocytosis

What type of collagen is exocytosed from the cell? How does it become the next type of collagen?

Procollagen; cleavage of non-helical ends (it is now tropocollagen)

What extracellular enzyme cleaves the procollagen ends to form tropocollagen? What enzyme then cross-links lysine residues to form collagen fibrils?

Procollagen peptidase; lysyl oxidase

What happens to turn collagen fibrils into collagen fibers?

Cross-linking by FACIT fibers and proteoglycans

What types of cells secrete elastic fibers?

Fibroblasts, chondroblasts, smooth muscle cells

What dye can stain elastic fibers black or dark blue?

Orcein

Which collagen types form long fibers?

I, II, III

Which collagen type(s) forms a network?

Which collagen type(s) forms anchoring fibrils?

VII

What gives collagen its impressive tensile strength?

Its triple helix structure

What three proteins are synthesized and released into the extracellular space to form elastic fibers? What protein is released with them to serve as a connecting bridge between the fibers?

**Tropoelastin**, **fibrillins** (1 and 2), and **fibulin** (1); desmosine

What are two major types of mast cell? Which of the two is T cell -dependent?

Connective tissue mast cells, mucosa mast cells (found largely in the lamina propria of the intestines and lungs); mucosa mast cells

What type of leukocyte is found in large numbers in the lamina propria of the intestines and lungs and is T cell -dependent?

Mucosa mast cells

Describe the general make-up of a proteoglycan aggregate. Liken it to a pine/Christmas tree if that helps.

A central hyaluronan protein *(like the trunk of a Christmas tree)*; core proteins extending out from the central protein *(the branches of the tree)*; glycosaminoglycans extending off the core proteins (e.g. keratan sulfate, condroitin sulfate) *(the pine needles of the tree)*

What part of a proteoglycan aggregate is responsible for the viscosity of this substance?

The core protein proteoglycans ## Footnote *(the Christmas tree branches)*

What parts of a proteoglycan aggregate are made up of glycosaminoglycans?

The axial protein (often hyaluronic acid); the GAG chains (e.g. keratan sulfate, chondroitin sulfate)

What is a proteoglycan?

The core protein with attached GAG chains

In discussing proteoglycan aggregates, where do adhesive glycoproteins come into play?

As small, globular proteins (with short carbohydrate chains) that are attached to the proteoglycan aggregate (e.g. laminin, fibronectin)

What is another term for the proteoglycan aggregates made up of proteoglycans, glycosaminoglycans, and glycoproteins?

Ground substance

What type of dense connective tissue is found in ligaments and tendons? What type of dense connective tissue is found in the dermis?

Dense **regular** connective tissue; dense **ir****regular** connective tissue

Which is more prevalent in loose connective tissue, fibers or ground substance & cells?

Ground substance & cells

What category of connective tissue is bone marrow? What category of connective tissue is the lamina propria of the GI tract?

Reticular loose (areolar)

What are a few types of specialized connective tissue in the body?

Adipose, cartilage, bone, reticular (bone marrow), blood

**True/False.** The loose connective tissue of the body is not very vascular.

False.

An osteoclast is basically a differentiated/specialized \_\_\_\_\_\_\_\_\_\_\_\_. An osteoblast is basically a differentiated/specialized \_\_\_\_\_\_\_\_\_\_\_\_.

Macrophage; fibroblast